[FFmpeg-devel] Stream with Closed caption does not set appropriate flag

Reimar Döffinger Reimar.Doeffinger at gmx.de
Thu Mar 6 20:46:58 CET 2014

On Thu, Mar 06, 2014 at 03:00:12PM +0530, anshul wrote:
> currently Video Stream Interlaced with Closed caption does not show
> anywhere.

Because we cannot currently extract it, and in general extracting CC
data as a separate stream is problematic since it is designed to be
reordered by the video decoder along with the image.
It's of course solvable but a bit of an effort.

> I was looking to enhance the code so that user get idea that closed caption
> is there inside Video stream
> would it be good idea if I add the information in the streams and set the
> stream's disposition flag to AV_DISPOSITION_HEARING_IMPAIRED
> As in comment shown with below flag and definition of closed caption match a
> lot
> #define AV_DISPOSITION_HEARING_IMPAIRED  0x0080  /**< stream for hearing
> impaired audiences */

None of the CC content I have seen is for hearing impaired, they were
all plain ordinary subtitles.
Hearing impaired content means that you will have text like
"*explosion*" and "(music playing)", i.e. all relevant sounds are
transformed into text, not just speech.

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